About Gillian O'Reilly Gillian O'Reilly is a writer and editor from Toronto, ON. She and Cora Lee also co-authored The Great Motion Mission: A Surprising Story of Physics in Everyday Life. She lives in Toronto, ON, Canada. Books by Gillian O'Reilly The Great Number Rumble Revised Edition by (author) Cora Lee & Gillian O'Reilly illustrated by Lil Crump Ages 9 to 12 Grades 4 to 7 Slangalicious Where We Got that Crazy Lingo by (author) Gillian O'Reilly illustrated by Krista Johnson